The present invention relates to a disc cartridge having a disc-shaped recording medium, such as an optical disc held therein, and to a recording and/or reproducing apparatus, employing the disc cartridge as a recording medium.
Up to now, a disc cartridge, having a disc-shaped recording medium, such as an optical disc, rotatably housed therein, which disc cartridge is loaded on a disc recording and/or reproducing apparatus, as the disc-shaped recording medium is housed therein, has been in use extensively. This sort of the disc cartridge, comprising a disc-shaped recording medium, housed in a main cartridge body unit, can be loaded on or unloaded from the disc recording and/or reproducing apparatus, with the disc-shaped recording medium in a protected state.
As this sort of the disc cartridge, such a one comprising a disc-shaped recording medium, housed for rotation in a rectangular-shaped main cartridge body unit, is in widespread use.
Meanwhile, in a disc cartridge, attempts are being made to reduce its size in keeping with the size of the disc-shaped recording medium, housed therein, with a view to reducing the size of the disc recording and/or reproducing apparatus, assuring facilitated handling of the disc cartridge, and to reducing the cartridge material and reducing the production cost.
With the disc cartridge, demand is also raised for increasing the recording capacity, in addition to reducing its size. The demand for increasing the recording capacity for the information signals may be met by increasing the recording density and by increasing the recording area provided on the disc-shaped recording medium.
Such a disc cartridge in which the cartridge size is reduced in keeping with the disc-shaped recording medium housed therein is disclosed in the Japanese Laid-Open Patent Publication H-11-353845.
With the disc cartridge, disclosed in Patent Publication 1, the size of the disc cartridge itself is reduced by having a substantially arcuate lateral surface, acting as an inserting end into the recording and/or reproducing apparatus.
The disc cartridge, disclosed in the above Publication, includes a recording and/or reproducing aperture, opened/closed by a shutter member provided to a main cartridge body unit, having an optical disc housed therein, and the optical disc is partially exposed to outside via this recording and/or reproducing aperture. The information signals are recorded and/or reproduced for the optical disc as an optical pickup of a recording and/or reproducing head part is exposed to outside the main cartridge body unit via this recording and/or reproducing aperture.
With the recording and/or reproducing apparatus, employing this disc cartridge as a recording medium, the optical pickup is moved along the radius of the optical disc, at a position spaced apart from the disc cartridge to scan the signal recording area of the optical disc with a light beam to record and/or reproduce the information signals. With the recording and/or reproducing apparatus, recording and/or reproducing the optical disc in accordance with this system, the optical pickup is moved at a position spaced apart from the disc cartridge, and hence there are imitations to reducing the thickness of the apparatus by reducing its height.
Meanwhile, in disc cartridges, used up to now, inclusive of the disc cartridge disclosed in the Japanese Laid-Open Patent Publication H-11-353845, the recording and/or reproducing aperture for exposing the signal recording area of the disc-shaped recording medium to outside is formed in a plane of the main cartridge body unit. In the case of this sort of the disc cartridge, the recording and/or reproducing head has to be moved within the range of the recording and/or reproducing aperture formed in the plane of the main cartridge body unit, in order to scan the signal recording area of the disc-shaped recording medium, with the result that the signal recording area cannot be extended efficiently up to the outer rim of the disc-shaped recording medium.
When an optical disc, in which attempts have been made for increasing the recording density, is used as a disc-shaped recording medium, an optical disc, having an objective lens of a high numerical aperture (NA), is used as a recording and/or reproducing head, for further reducing the beam diameter of a light beam scanning the signal recording area of the optical disc. With the use of this sort of the optical pickup, it is necessary for the optical pickup to be at a position close to the optical disc and, to this end, it is necessary for at least a portion of the optical pickup to be introduced into the disc cartridge. If the portion of the optical pickup intrudes into the disc cartridge, there is placed limitation to the area of possible movement of the optical pickup, such that the signal recording area cannot efficiently be extended up to the outer rim of the disc-shaped recording medium.
That is, with the conventional disc cartridge, it is difficult to enlarge the signal recording area of the disc-shaped recording medium, arranged therein, so that it is difficult to increase the recording capacity if the disc-shaped recording medium is to be reduced in size at the same time.